The history of suspended cat scratching devices have generally involved solutions which mount off an existing dwelling door knob and limit the effective size and height of the scratching surface to minimize blockage of a door or doorway. The history of trackball devices presents them only in a floor resting fashion which provides for top attack.
Those well-acquainted with domestic cats will know that often the clawing of a sofa arm by a cat is performed to stretch-out and align the cats vertebra and not simply to tear apart the sofa arm. A cat will prefer a higher surface for greater stretch therefore a suspended scratching post which may be above the height of a door knob provides a more enticing surface for stretching than a sofa arm.
While large floor standing scratching posts do provide scratching surfaces of a height and size that may be as attractive to a cat as a sofa arm , such devices require a large area of dedicated floor space to host the base of the unit, and such space dedications may be impractical. Therefore, a over-the-door mounted scratching post which provides the volume and height of a large cylindrical floor standing scratching post without requiring the large area of dedicated floor space provides a desirable large scratching surface without the associated loss of floor space and without creating room obstructions.
The door knob mounted scratching surfaces taught by U.S. Pat. No. 3,085,551 issued to Helmer and U.S. Pat. No. 4,611,556 issued to Frank provide a well-anchored small light-weight and collapsible scratching surface held below the door knob or against a wall or cage. The door mounted vertical scratching surface taught by Helmer is suspended off a doorknob and all horizontal movement is eliminated by a tension bearing spring anchored to the door knob mount which pulls against a corresponding "U" shaped sleeve which is placed under the door.
The suspended toy and feline exerciser taught in applicant's U.S. Pat. No. 5,474,032 teaches a system of tethered feline target objects suspended from the top edge of a dwelling door which provides for increased erratic movement to encourage a cat to play on its own.
The movement of a target ball within a track has been demonstrated to provide a cat or incentive to play on its own. Often a trackball enclosure such a as that taught in U.S. Pat. No. 4,722,299, issued to Mohr will be pushed by the cat's play under the edge of the very sofa or chair, the toy is designed to draw the cat away from, resulting in a excited cat near furniture. A raised track with rolling ball, not found in the prior art, and anchored to a door provides the enticement of the rolling target safely suspended away from furniture.
None of the solutions provide a durable removable over-the-door mounted scratching surface which is self-dampening to limit swing when the door is opened or closed large enough to be as engaging to a cat as a sofa arm and which may be suspended off the top of an existing dwelling door and which does not impair opening or closure of the door. Nor do these solutions provide a raised trackball which a cat may attack from below.